A method for preparing heavy media for coal preparation using red mud

Abstract

This invention provides a method for preparing heavy media for coal preparation using red mud. The method includes: sequentially grinding and screening the red mud to obtain ground material; subjecting the ground material to reduction roasting activation treatment to obtain roasted clinker; mixing the roasted clinker with hydrochloric acid for acid leaching, followed by solid-liquid separation to obtain acid leaching solution and acid leaching residue; drying the acid leaching residue, and then sequentially grinding and screening it a second time to obtain a weighted powder; mixing the weighted powder, water, coal slime, and clay minerals, and adjusting the suspension density to obtain a heavy media suspension for coal preparation. The method described in this invention utilizes red mud solid waste to produce heavy media products, achieving resource recovery of iron from red mud and increasing the added value of red mud resource utilization.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a method for preparing coal preparation heavy media using red mud. Background Technology

[0002] Red mud is an industrial solid waste discharged during the alumina production process from bauxite, named for its resemblance to reddish soil. Due to its high alkalinity, fine particle size, and complex composition, red mud is difficult to utilize as a resource. Large quantities of red mud are generated but not effectively utilized, primarily disposed of through stockpiling, causing serious environmental pollution and ecological damage. Utilization methods for red mud mainly include the recovery of valuable elements, the preparation of functional materials, and its application in building materials. Among these, the rich content of elements such as iron, aluminum, silicon, and sodium in red mud makes element recovery an important method for its resource utilization.

[0003] CN115058587A discloses a method for the resource utilization of red mud, comprising the following steps: Step a, microwave roasting: drying rice husks and red mud, grinding, mixing, pressing into tablets, and roasting in a microwave reactor; the mixing ratio is 6:1 to 2:1 by weight of red mud to rice husks; the microwave roasting temperature is 500℃ to 1000℃, the microwave roasting time is 10 min to 30 min, and the microwave power is 1 kW to 1.4 kW; Step b, separation: cooling the sintered blocks obtained in step a to room temperature, ball milling, slurry preparation, and magnetic separation to obtain iron concentrate and magnetic separation slag; ball milling for 5 min to 40 min, slurry liquid-to-solid ratio of 200 to 500 ml / g, and magnetic separation current of 1 A to 5 A. This method not only recovers iron from red mud but also improves the activity of inorganic components in the magnetic separation slag, enabling the magnetic separation slag to be directly used in large quantities as raw material for red mud-based polymers, building bricks, etc.

[0004] CN104291540A discloses a method for the resource-based treatment of red mud, comprising: 1) adding red mud to a soda ash solution for causticization reaction, and filtering to obtain filter cake A; 2) adding filter cake A to hydrochloric acid for acidolysis reaction, and filtering to obtain filtrate B; 3) adding hydrogen peroxide solution to filtrate B for oxidation reaction, followed by adding phosphoric acid for neutralization reaction, and filtering to obtain filtrate C; 4) adding sodium sulfide solution to filtrate C for precipitation reaction, and filtering to obtain filtrate D; 5) adding caustic soda solution to filtrate D for neutralization reaction, and filtering to obtain filtrate E; 6) adding ammonia water to filtrate E for neutralization reaction, and filtering to obtain filtrate F; 7) adding caustic soda solution to filtrate F for precipitation reaction, and filtering to obtain filtrate G; 8) adding hydrochloric acid to filtrate G, and after evaporation and crystallization, filtering to obtain filter cake H. This treatment method realizes the resource-based treatment and comprehensive recycling of red mud, and has good economic, environmental and social benefits.

[0005] CN116377207A discloses a method for the resource utilization of red mud dealkalization, comprising the following steps: adding red mud and titanium dioxide waste acid to deionized water, adding hydrogen peroxide, stirring thoroughly to form a mixed liquid, filtering to obtain a dealkalized clear liquid and dealkalized residue; adjusting the pH of the dealkalized clear liquid to neutral, then performing solid-liquid separation to obtain a second residue and a second clear liquid; adding calcium oxide to the second clear liquid, collecting the gas generated during the process by spraying, and performing solid-liquid separation to obtain a third residue and a third clear liquid, which are then recovered; and evaporating and concentrating the spray liquid for recovery. This method enriches the iron content in the dealkalized red mud while simultaneously dealkalizing it, facilitating iron recovery; the obtained second residue is ferric hydroxide, which can be directly used as iron concentrate for smelting; the third clear liquid is concentrated by evaporation to obtain concentrated ammonia water for reuse, reducing ammonia water consumption; and a small amount of solid waste calcium sulfate is generated, truly achieving solid waste reduction, resource utilization, and harmlessness.

[0006] However, the above methods are relatively complex and have high energy consumption, and need further improvement and optimization. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for preparing coal preparation heavy media using red mud. By sequentially subjecting the ground and sieved red mud to reduction roasting, acid leaching, material grinding and density control, a coal preparation heavy media suspension and an acid leaching solution for preparing polyaluminum ferric silicate flocculant are obtained. The method is simple, and the reduction roasting and acid leaching require low temperatures, which significantly reduces the reaction energy consumption and is suitable for large-scale application.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] This invention provides a method for preparing heavy media for coal preparation using red mud, the method comprising the following steps:

[0010] (1) Material grinding: Red mud is successively ground and screened to obtain ground material;

[0011] (2) Calcination and activation: The ground material is subjected to reduction calcination and activation treatment to obtain calcined clinker;

[0012] (3) Acid leaching: The roasted clinker is mixed with hydrochloric acid and acid leaching is performed. After solid-liquid separation, acid leaching solution and acid leaching residue are obtained.

[0013] (4) Grinding of materials: After drying the acid leaching residue, it is ground and then screened in sequence to obtain a weighted powder;

[0014] (5) Density control: Mix the weighting powder, water, coal slime and clay minerals to control the density of the suspension and obtain a coal preparation heavy medium suspension.

[0015] A weighting medium is a high-density solid particle used to prepare heavy medium suspensions, and it can be widely used in the gravity separation stage of processes such as coal preparation and mineral processing. Traditional gravity separation processes use heavy media such as tribromomethane, tetrabromoethane, diiodomethane, and mercuric iodide, which are generally expensive and harmful to human health. Therefore, in industry, weighting mediums are used to prepare heavy suspensions as heavy media for coal preparation. Moreover, density control is crucial in preparing weighting medium suspensions. If the raw materials for the suspension do not include coal slime or clay minerals, the cost of coal preparation will increase significantly, and the viscosity of the suspension will decrease, which is detrimental to its stability. Furthermore, an unreasonable mass ratio of the raw materials will result in poor coal preparation performance when using the suspension.

[0016] The method for preparing heavy media for coal preparation using red mud described in this invention transforms and enriches iron oxide (Fe2O3) in red mud into magnetic iron (Fe3O4) through reduction roasting activation and acid leaching. This process is carried out under medium-temperature conditions, effectively reducing reaction energy consumption. After sieving, the prepared magnetic iron powder is mixed with water, coal slime, and clay minerals, and the suspension density is adjusted to obtain a heavy media suspension applicable to the coal preparation field. At the same time, this method utilizes the alkaline components (calcium nepheline, hydrogarnet, etc., free alkali, etc.) in red mud, which has a certain promoting effect on the transformation of the iron phase in the above-mentioned reduction roasting activation process. This method further utilizes the aluminum-silicon components (calcium nepheline, hydrogarnet, etc.) in red mud. The acid leaching solution obtained after acid leaching can be used to prepare polyaluminum-iron silicate flocculants, etc., with no waste discharge, making it clean and environmentally friendly.

[0017] The method for preparing coal preparation heavy media using red mud described in this invention, compared with the existing method of recovering Fe2O3 from red mud using magnetic separation, does not produce non-magnetic separation residue, has no waste discharge, and is environmentally friendly.

[0018] Preferably, the red mud in step (1) includes any one or at least two of Bayer process red mud, sintering process red mud, or combined process red mud, wherein typical but non-limiting combinations include a combination of Bayer process red mud and sintering process red mud, a combination of combined process red mud and Bayer process red mud, or a combination of sintering process red mud and combined process red mud.

[0019] Preferably, the particle size of the grinding material in step (1) is <150um, for example, it can be 149um, 120um, 100um, 90um, 75um mesh or 60um, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the reduction roasting activation treatment in step (2) is carried out in an atmosphere furnace.

[0021] Preferably, the volume fraction of reducing gas in the atmosphere of the reduction roasting activation treatment is 10% to 50%, which has the advantage of efficiently and rapidly reducing the iron-containing phase (Fe2O3) in the ground material to the magnetic phase (Fe3O4), and has the advantage of lower material requirements compared with solid reducing agents.

[0022] Preferably, the reducing gas includes hydrogen and / or carbon monoxide.

[0023] Preferably, the temperature of the reduction roasting activation treatment in step (2) is 520 to 580°C, for example, it can be 520°C, 530°C, 540°C, 550°C, 560°C, 570°C or 580°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] The reduction roasting activation treatment described in this invention is performed at a temperature of 520–580°C, which is relatively low and results in low reaction energy consumption, thus reducing the cost of resource utilization of red mud.

[0025] Preferably, the reduction calcination activation treatment time is 5 to 25 minutes, for example, it can be 5 minutes, 8 minutes, 10 minutes, 12 minutes, 15 minutes, 20 minutes or 25 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Preferably, the acid leaching in step (3) is carried out in a reaction vessel.

[0027] Preferably, the concentration of hydrochloric acid in step (3) is 10 to 20 wt.%, for example, it can be 10 wt.%, 12 wt.%, 14 wt.%, 15 wt.%, 17 wt.%, 18 wt.%, or 20 wt.%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] The present invention preferably uses hydrochloric acid with a concentration of 10-20 wt.%, which achieves efficient recovery of iron from red mud and thus improves the quality of coal preparation heavy medium suspension.

[0029] Preferably, the liquid-solid mass ratio of hydrochloric acid to calcined clinker in the acid leaching is (6-8):1, for example, it can be 6:1, 6.3:1, 6.5:1, 7:1, 7.2:1, 7.5:1 or 8:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] The liquid-solid mass ratio of hydrochloric acid to roasted clinker in the acid leaching process described in this invention refers to the ratio of the mass of the hydrochloric acid solution to the mass of the roasted clinker, expressed in g / g.

[0031] Preferably, the acid leaching temperature in step (3) is 10 to 25°C, for example, it can be 10°C, 12°C, 15°C, 18°C, 20°C, 22°C or 25°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Preferably, the acid leaching time is 30 to 90 minutes, for example, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes or 90 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the acid leaching solution is used to prepare polyaluminum ferric silicate flocculant.

[0034] Preferably, the particle size of the weighting powder in step (4) is <75um, for example, it can be 74um, 70um, 65um, 60um, 55um, 50um or 45um mesh, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the heavy medium powder, coal slime and clay minerals in step (5) constitute the solid phase of the coal preparation heavy medium suspension.

[0036] Preferably, the mass fraction of the weighting powder in the solid phase is 65% to 75%, for example, it can be 65%, 65.5%, 66%, 70%, 71%, 72%, 74% or 75%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the mass fraction of coal slime in the solid phase is 15% to 25%, for example, it can be 15%, 17%, 19%, 20%, 21%, 23%, 24% or 25%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the mass fraction of clay minerals in the solid phase is 5% to 10%, for example, it can be 5%, 5.5%, 6%, 7%, 8%, 9%, 9.5% or 10%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] In this invention, the mass fractions of coal slime and clay minerals in the solid phase are preferably within a specific range. When the relative content of coal slime is low, the stability of the suspension will be poor; when the relative content of coal slime is high, the fluidity of the suspension will also be poor. When the relative content of clay minerals is low, the stability of the suspension will be insufficient; when the relative content of clay minerals is high, the fluidity of the suspension will also be deteriorated.

[0040] Preferably, the clay minerals in step (4) include kaolin and / or montmorillonite.

[0041] Preferably, the liquid-to-solid mass ratio of the coal preparation heavy medium suspension is (193-131):1, for example, it can be 193:1, 190:1, 180:1, 170:1, 150:1, 140:1, 135:1 or 131:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] The liquid-to-solid mass ratio of the coal preparation heavy medium suspension described in this invention refers to the ratio of the mass of water to the mass of the solid phase, expressed in g / g.

[0043] Preferably, the density of the coal preparation heavy medium suspension is 1.3–1.5 g / cm³. 3 For example, it could be 1.3 g / cm³ 3 1.35g / cm 3 1.38g / cm 3 1.4g / cm 3 1.43 g / cm 3 1.45g / cm 3 Or 1.5g / cm 3 This applies to, but is not limited to, the listed values; other unlisted values ​​within this range also apply.

[0044] The density of the coal preparation heavy medium suspension obtained by the method of the present invention is 1.3-1.5 g / cm³. 3 It has the advantages of low viscosity and high stability.

[0045] The solid-liquid separation described in this invention is not limited, and any method known to those skilled in the art for solid-liquid separation can be used, such as filtration, sedimentation, or centrifugation.

[0046] As a preferred technical solution of the present invention, the method includes the following steps:

[0047] (1) Material grinding: The red mud is successively ground and screened to obtain a ground material with a particle size of <150um; the red mud includes any one or at least a combination of two of Bayer process red mud, sintering process red mud or combined process red mud.

[0048] (2) Calcination activation: The ground material is subjected to reduction calcination activation treatment at a temperature of 520-580℃ for 5-25 minutes in an atmosphere furnace to obtain calcined clinker; the volume fraction of reducing gas in the atmosphere of the reduction calcination activation treatment is 10%-50%; the reducing gas includes hydrogen and / or carbon monoxide.

[0049] (3) Acid leaching: The roasted clinker is mixed with hydrochloric acid of 10-20 wt.% at a liquid-to-solid mass ratio of (6-8):1 and acid leaching is carried out at a temperature of 10-25°C for 30-90 minutes. After solid-liquid separation, acid leaching solution and acid leaching residue are obtained. The acid leaching solution is used to prepare polyaluminum ferric silicate flocculant.

[0050] (4) Material grinding: After drying the acid leaching residue, it is ground and then screened in sequence to obtain a weighted powder with a particle size of <75um;

[0051] (5) Density control: The weighting powder, coal slime, and clay minerals are mixed in a certain proportion, and water is added to control the density of the suspension to obtain a coal preparation heavy medium suspension; the heavy medium powder, coal slime, and clay minerals constitute the solid phase of the coal preparation heavy medium suspension; the mass fraction of the weighting powder in the solid phase is 65%–75%; the mass fraction of the coal slime in the solid phase is 15%–25%; the mass fraction of the clay minerals in the solid phase is 5%–10%; the liquid-solid mass ratio of the coal preparation heavy medium suspension is (193–131):1; the density of the coal preparation heavy medium suspension is 1.3–1.5 g / cm³. 3 The clay minerals include kaolin and / or montmorillonite.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] The method for preparing coal preparation heavy media provided by this invention involves medium-temperature reduction roasting of red mud followed by low-temperature acid leaching. The resulting acid leaching solution can be used to prepare polyaluminum-iron polysilicate flocculant. The acid leaching residue is mixed with coal slime and clay minerals to obtain a coal preparation heavy media suspension. The entire process is environmentally friendly with no waste discharge, low reaction energy consumption, and broad application prospects. Attached Figure Description

[0054] Figure 1 This is a schematic flowchart of a method for preparing coal preparation heavy media using red mud, provided by the present invention.

[0055] Figure 2 These are product images and XRD patterns of the weighted powder and coal preparation heavy medium suspension obtained in Example 1. Detailed Implementation

[0056] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0057] This invention provides a method for preparing heavy media for coal preparation using red mud, the process flow diagram of which is shown below. Figure 1 As shown.

[0058] The method includes the following steps:

[0059] (1) Material grinding: Red mud is successively ground and screened to obtain ground material;

[0060] (2) Calcination and activation: The ground material is subjected to reduction calcination and activation treatment to obtain calcined clinker;

[0061] (3) Acid leaching: The roasted clinker is leached with hydrochloric acid, and after solid-liquid separation, acid leaching solution and acid leaching residue are obtained;

[0062] (4) Grinding of materials: After drying the acid leaching residue, it is ground and then screened in sequence to obtain a weighted powder;

[0063] (5) Density control: Mix the weighting powder, water, coal slime and clay minerals to control the density of the suspension and obtain a coal preparation heavy medium suspension.

[0064] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0065] The red mud used in the following examples and comparative examples was taken from Bayer process red mud from an aluminum company in Shanxi Province. The chemical composition of the red mud is shown in Table 1 below.

[0066] Table 1

[0067]

[0068] Example 1

[0069] This embodiment provides a method for preparing coal preparation heavy media using red mud, the method comprising the following steps:

[0070] (1) Material grinding: Red mud is successively ground and screened to obtain ground material with a particle size of 150um;

[0071] (2) Calcination activation: The ground material is subjected to reduction calcination activation treatment at a temperature of 540°C for 15 minutes in an atmosphere furnace to obtain calcined clinker; the carbon monoxide volume fraction in the atmosphere of the reduction calcination activation treatment is 30%.

[0072] (3) Acid leaching: The roasted clinker was mixed with hydrochloric acid at a liquid-to-solid mass ratio of 7:1 and acid leaching was carried out at a temperature of 20°C for 90 min. After solid-liquid separation, acid leaching solution and acid leaching residue were obtained. The acid leaching solution was used to prepare polyaluminum ferric silicate flocculant.

[0073] (4) Material grinding: After drying the acid leaching residue, it is ground and then screened in sequence to obtain a weighted powder with a particle size of 75 μm.

[0074] (5) Density control: The solid phase of the coal preparation heavy medium suspension consists of heavy medium powder, coal slime, and clay mineral kaolin. The mass fraction of the heavy medium powder in the solid phase is 71%; the mass fraction of the coal slime in the solid phase is 19%; and the mass fraction of the clay mineral kaolin in the solid phase is 10%. Water is added to adjust the liquid-solid mass ratio of the suspension to 154:1, resulting in a density of 1.36 g / cm³. 3 Coal preparation heavy medium suspension

[0075] The product images and XRD patterns of the weighted powder and coal preparation heavy medium suspension obtained in this embodiment are as follows: Figure 2 As shown, from Figure 2 It can be seen that the main mineral component in the weighted powder is Fe3O4, which can form a relatively stable suspension in water.

[0076] Example 2

[0077] This embodiment provides a method for preparing coal preparation heavy media using red mud, the method comprising the following steps:

[0078] (1) Material grinding: Red mud is ground and screened in sequence to obtain ground material with a particle size of 120um;

[0079] (2) Calcination activation: The ground material is subjected to reduction calcination activation treatment at a temperature of 550°C for 20 minutes in an atmosphere furnace to obtain calcined clinker; the volume fraction of hydrogen in the atmosphere of the reduction calcination activation treatment is 40%.

[0080] (3) Acid leaching: The roasted clinker was mixed with hydrochloric acid at a liquid-to-solid mass ratio of 6:1 and subjected to acid leaching at a temperature of 20°C for 90 min. After solid-liquid separation, acid leaching solution and acid leaching residue were obtained. The acid leaching solution was used to prepare polyaluminum ferric silicate flocculant.

[0081] (4) Grinding of materials: After drying the acid leaching residue, it is ground and then screened in sequence to obtain a weighted powder with a particle size of 62 μm.

[0082] (5) Density control: The solid phase of the coal preparation heavy medium suspension consists of heavy medium powder, coal slime, and clay mineral montmorillonite. The mass fraction of the heavy medium powder in the solid phase is 70%; the mass fraction of the coal slime in the solid phase is 24%; and the mass fraction of the clay mineral montmorillonite in the solid phase is 6%. Water is added to adjust the liquid-solid mass ratio of the suspension to 162:1, resulting in a density of 1.34 g / cm³. 3 Coal preparation heavy medium suspension.

[0083] The quality data of the weighted powders obtained in Examples 1 and 2 are shown in Table 2.

[0084] Table 2

[0085] Example 1 Example 2 Iron recovery rate (%) 88.46 89.27 Iron grade (%) 56.40 55.14 Product magnetite content (%) 95.22 95.13 -45μm particle size composition (%) 93.27 92.89 <![CDATA[True density (g / cm 3 )]]> 4.62 4.64 External moisture (%) 6.5 6.8

[0086] Example 3

[0087] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for step (2), where the carbon monoxide volume fraction is 5%, the method is the same as in Example 1.

[0088] Example 4

[0089] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for step (2) where the carbon monoxide volume fraction is 80%, the method is the same as in Example 1.

[0090] It can be seen from the combined examples 1, 3 and 4 that the volume fraction of activated carbon monoxide in the reduction roasting of example 3 is low, which leads to a decrease in the iron recovery rate of the weighted powder, and further results in the proportion of magnetic materials in the weighted powder being too low to meet the national standard, thus affecting the coal preparation effect; the volume fraction of activated carbon monoxide in the reduction roasting of example 4 is too high, which will lead to the discharge of carbon monoxide after the reaction is complete, further resulting in energy waste and even harm to human health.

[0091] Example 5

[0092] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for the temperature of the reduction roasting activation treatment in step (2) being 400°C, the method is the same as in embodiment 1.

[0093] Example 6

[0094] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for the temperature of the reduction roasting activation treatment in step (2) being 800℃, the method is the same as in embodiment 1.

[0095] It can be seen from the combined results of Examples 1, 5, and 6 that the reduction roasting activation treatment temperature in Example 5 is too low, which leads to incomplete reaction and the generation of a large amount of FeO. This further results in the proportion of magnetic material in the weighted powder being too low and not meeting the national standard, thus affecting the coal preparation effect. The reduction roasting activation treatment temperature in Example 6 is too high, which leads to over-reaction and the generation of a large amount of elemental Fe, thus affecting the coal preparation effect.

[0096] Example 7

[0097] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for the concentration of hydrochloric acid in the acid leaching in step (3) being 7 wt.%, the method is the same as in Example 1.

[0098] Example 8

[0099] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for the concentration of hydrochloric acid in the acid leaching in step (3) being 27 wt.%, the method is the same as in Example 1.

[0100] As can be seen from Examples 1, 7, and 8, the low concentration of hydrochloric acid in the acid leaching process of Example 7 leads to a decrease in the iron recovery rate of the weighted powder, which further results in an excessively low proportion of magnetic materials in the weighted powder, failing to meet national standards and thus affecting the coal preparation effect. In Example 8, the high concentration of hydrochloric acid in the acid leaching process leads to a decrease in the iron recovery rate of the weighted powder, which further results in an excessively low proportion of magnetic materials in the weighted powder, failing to meet national standards and thus affecting the coal preparation effect.

[0101] Example 9

[0102] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for the acid leaching temperature of 5°C in step (3), the method is the same as in Example 1.

[0103] Example 10

[0104] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for the acid leaching temperature of 70°C in step (3), the method is the same as in Example 1.

[0105] Based on the combined results of Examples 1, 9, and 10, it can be seen that the acid leaching temperature in Example 9 is relatively low, which leads to a large amount of silicon precipitation in the weighted powder, affecting the iron recovery rate. This further results in the proportion of magnetic materials in the weighted powder being too low and failing to meet national standards, thus affecting the coal preparation effect. In Example 10, the acid leaching temperature is too high, which leads to a large amount of iron dissolution during the reaction, affecting the iron recovery rate. This further results in the proportion of magnetic materials in the weighted powder being too low and failing to meet national standards, thus affecting the coal preparation effect.

[0106] Example 11

[0107] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for step (5) where water is added to adjust the liquid-solid mass ratio of the suspension to 100:1, the method is the same as in embodiment 1.

[0108] Example 12

[0109] This embodiment provides a method for preparing coal preparation heavy media using red mud. Except for step (5) where water is added to adjust the liquid-solid mass ratio of the suspension to 250:1, the method is the same as in embodiment 1.

[0110] It can be seen from the combined examples 1 and 11-12 that the low amount of water added in example 11 leads to a significant increase in the viscosity of the suspension and a decrease in its flow performance; while the high amount of water added in example 12 leads to a decrease in the stability of the suspension.

[0111] Comparative Example 1

[0112] This comparative example provides a method for preparing coal preparation heavy media using red mud. The method is the same as in Example 1 except that the clay mineral kaolin mentioned in step (5) is replaced with quartz sand.

[0113] As can be seen from Example 1 and Comparative Example 1, when density control is performed in step (5), replacing montmorillonite with quartz sand leads to the disappearance of the colloidal-like interaction between coal slime and clay minerals, resulting in a significant deterioration in the stability of the suspension. This demonstrates that the present invention, by mixing the weighted powder with water, coal slime, and clay minerals to control the suspension density, can obtain a coal preparation heavy medium suspension with suitable density, which can be widely used in the coal preparation field.

[0114] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing coal preparation heavy media using red mud, characterized in that, The method includes the following steps: (1) Grinding of materials: Red mud is successively ground and screened to obtain ground material; (2) Calcination activation: The ground material is subjected to reduction calcination activation treatment to obtain calcined clinker; (3) Acid leaching: The roasted clinker is mixed with hydrochloric acid and acid leaching is performed. After solid-liquid separation, acid leaching solution and acid leaching residue are obtained. (4) Grinding of materials: After drying the acid leaching residue, it is ground and then screened in sequence to obtain a weighted powder; (5) Density control: The weighted powder, water, coal slime and clay minerals are mixed to control the density of the suspension and obtain a coal preparation heavy medium suspension.

2. The method according to claim 1, characterized in that, The red mud in step (1) includes any one or a combination of at least two of Bayer process red mud, sintering process red mud, or combined process red mud.

3. The method according to claim 1 or 2, characterized in that, The particle size of the grinding material in step (1) is <150um.

4. The method according to claim 1, characterized in that, The reduction roasting activation treatment in step (2) is carried out in an atmosphere furnace.

5. The method according to claim 1, characterized in that, The volume fraction of reducing gas in the atmosphere of the reduction roasting activation treatment in step (2) is 10%~50%.

6. The method according to claim 5, characterized in that, The reducing gas includes hydrogen and / or carbon monoxide.

7. The method according to claim 1, characterized in that, The temperature of the reduction roasting activation treatment in step (2) is 520~580°C.

8. The method according to claim 1, characterized in that, The reduction roasting activation treatment in step (2) takes 5 to 25 minutes.

9. The method according to claim 1, characterized in that, The acid leaching in step (3) is carried out in a reaction vessel.

10. The method according to claim 1, characterized in that, The concentration of hydrochloric acid in step (3) is 10~20 wt.%.

11. The method according to claim 1, characterized in that, The liquid-solid mass ratio of hydrochloric acid to roasted clinker in step (3) is (6~8):

1.

12. The method according to claim 1, characterized in that, The acid leaching temperature in step (3) is 10~25℃.

13. The method according to claim 1, characterized in that, The acid leaching time in step (3) is 30~90 min.

14. The method according to claim 1, characterized in that, The acid leaching solution in step (3) is used to prepare polyaluminum ferric silicate flocculant.

15. The method according to claim 1, characterized in that, The particle size of the weighted powder in step (4) is <75 μm.

16. The method according to claim 1, characterized in that, The solid phase of the coal preparation heavy medium suspension composed of the weighting powder, coal slime and clay minerals in step (5) is formed.

17. The method according to claim 16, characterized in that, The mass fraction of the weighted powder in the solid phase is 65%~75%.

18. The method according to claim 16, characterized in that, The mass fraction of coal slime in the solid phase is 15% to 25%.

19. The method according to claim 16, characterized in that, The mass fraction of clay minerals in the solid phase is 5% to 10%.

20. The method according to claim 16, characterized in that, The clay minerals include kaolin and / or montmorillonite.

21. The method according to claim 1, characterized in that, The liquid-solid mass ratio of the coal preparation heavy medium suspension in step (5) is (193~131):

1.

22. The method according to claim 1, characterized in that, The density of the heavy medium suspension in step (5) is 1.3~1.5 g / cm³. 3 .

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